1. Field of the Invention
The present invention relates to a pantagraph-type jack comprising a pair of lower arms disposed in an upward divergent shape and swingably connected at lower ends thereof to a pedestal, a pair of upper arms disposed in a downward divergent shape and swingably connected at upper ends thereof to load receiving base, upper ends of the lower arms and lower ends of the upper arms being connected to each other through first and second connecting shafts, respectively, and an externally threaded rod rotatably but axially non-movably supported on the first connecting shaft and threadedly engaged with a threaded bore provided in the second connecting shaft, and to a process for producing such a pantagraph-type jack.
2. Description of the Related Art
Such pantagraph-type jacks are already known, as disclosed, for example, in Japanese Patent Publication No. 3-6120.
Such a pantagraph-type jack is equipped in an automobile in many cases and hence, there is a strong demand for reducing the weight of the pantagraph-type jack. As disclosed in the above-described publication, however, in the known pantagraph-type jack, the externally threaded rod is formed of a solid and very weighty rounded rod, which is an obstacle to a reduction in weight.